1. Field of the Invention
The invention relates to a hand grip structure, and more particularly, to an anatomically configured hand grip for optimum transfer of prehensile forces to a gripped implement.
2. History of the Prior Art
The human hand is the principal means by which man grasps, lifts, and manipulates objects. Man uses his hand to hold objects in one of two general fashions. The first has been termed a precision grip. With this grip, primarily the fingers of the hand are involved and objects requiring very precise manipulation such as pencils, surgical scalpels, and other instruments are used. The other type of grip is referred to as a power grip and is one by which man grasps objects over which he desires to exert a maximum amount of power and force. Generally speaking, the shape of the object handled by the hand has very little to do with the type of grip employed and virtually all prehensile movements of the hand, wherein the object of the movement is to exert power and force over the object held involves the power grip.
Many different implements are intended to be grasped and moved by the hand and arm so as to effect some result. These implements include everything from tools such as hammers, axes and screw drivers to sporting equipment such as tennis rackets, golf clubs and baseball bats. With each of these implements one of the primary functions of its use is to move the implement with a substantial amount of power being exerted thereover.
In racket sports such as tennis, racketball and squash, it is desirable to move the racket with the hand and arm so as to exert a maximum amount of power and precision over the movement of the racket. This should be done while minimizing the fatigue in the hand and arm resulting from such movements. All of the force which is exerted over an implement such as a racket must travel through the portion of the racket handle which is grasped by the hand and conventionally known as the grip of the racket. Most conventional grips are generally uniform in cross section throughout their length. The grips normally have a cross-sectional shape which is generally circular, oval, or of some other regular shape (e.g. octagonal). In addition, such grips are usually wrapped with either strips of leather or some other nonslip material to improve the ability of the hand to grasp the surface and maximize the power and control which can be exerted over the implement.
In the power grip the object is held in the hand. If the object is elongate, it is generally placed axially along the palmar flexion creases with the thumb folded around in one direction and the fingers folded around in the other. In the power grip, the thumb and either the index or middle finger are in opposition to one another with the ring finger and little finger grasped tightly around the periphery of the object.
Grips of conventional uniform cross section along their length do not allow the hand to be postured in its most anatomically correct configuration so as to maximize either the power or the precision of movement exercised over the implement. Most implement grips are designed according to tradition rather than according to anatomical/physiological considerations and traditional designs do not necessarily provide the highest design/function relationship. In addition, the hand often tires quickly from repeated movement using such a uniform grip. Prior art implement grips such as those for tennis rackets, have been designed for improvement of the gripping surface to maximize utilization of the implement. In particular, U.S. Pat. No. 3,905,589 to Ballog discloses an improved tennis racket hand grip wherein the gripping surface is contoured to conform to the hand, and particularly the shape of the fingers and thumb, when held in a power grip. The Ballog patent includes contours on the gripping surface to receive the digits of the hand in both a forehand and backhand posture and specific indentations and recesses are formed in the gripping surface to receive the fingers and thumb in each of these two configurations. U.S. Pat. No. 3,868,110 to Jones discloses a similar approach to the improvement of tennis racket grips which also includes distinct indentations to receive the contours of the thumb and fingers in both the forehand and backhand positions. Increasing the surface area of interengagement between the hand and the grip increases the power which can be exerted over the implement. The intent of each of these two prior art patents is to use the finger recesses to maximize the surface area of contact between the hand and the grip in order to maximize the amount of strength and power which can be exerted over the racket by the arm and hand. However, increasing the amount of surface contact between the grip and the hand also increases the amount of compression of the tissues of the hand, thumb and fingers which restricts the blood supply thereto and reduces the delivery of oxygen to the muscles and other tissues of the hands. This increases the rate at which the hand fatigues and decreases the time period over which the hand can continue to exert a maximum amount of strength and power over the implement.
An additional disadvantage of prior art finger indentation grips is that hand sizes are all slightly different. Moreover, the precise hand posture which each player assumes in a forehand and in a backhand grip of the racket is also slightly different and does not necessarily conform to the precise configurations which are included in contoured prior art grips. Misalignment of the contoured surface of the hand creates even greater mismatch between the hand surface and the grip which degrades rather than increases the amount of power and precision of control over the racket.
It may also be seen that the contoured gripping surfaces of the prior art are only suitable for implements such as tennis rackets wherein the device is always used with a fixed position of rotation about the axis of the grip. That is, for implement handles where there must be the ability to grip the handle at any position of rotational symmetry, contoured grips are totally ineffective.
The grip of the present invention is rotationally symmetrical, permitting the hand to grasp the grip in a posture which improves the power and control which can be exerted over the implement. This is effected by allowing the hand to assume a position wherein each of the muscles which control movement of the fingers is in its resting position and thus able to exert maximum force over the grip. In addition, the grip of the present invention allows the hand to transfer a maximum amount of force through the fleshy portion of the hand located between the thumb and the forefinger. This requires little force to be exerted by the portion of the hand which overlies the metacarpal tunnel through which numerous veins, arteries, nerves and tendons controlling movement of the hand pass. Blood flow is thus not restricted and needless pressure is not applied to the nerves in that region. These features allow the hand to continue to apply a maximum amount of force and control over the grip without tiring due to a restricted flow of blood to the muscles and other tissues of the hand.